Virucidally effective facial tissues are now well known in the tissue industry. The most significant example of such a tissue is described in commonly owned copending application Ser. No. 447,581 filed Dec. 13, 1982 in the names of Shafi Hossain and Kenneth Smith (herein incorporated by reference). A foreign counterpart to that application issued in Canada on June 4, 1985, as Canadian Pat. No. 1,188,225 and is assigned to Kimberly-Clark Corporation.
The abovesaid application and patent describe, among other things, a tissue product containing a virucidally effective amount of certain carboxylic acids, particularly including citric acid and malic acid. Upon carrying out further research and development on this product an unusual and unexpected property was discovered. In particular, it was discovered that in some instances the perceived softness of the product decreased with aging. Although the decrease in softness appears to be linked to the relationship between the moisture level in the tissue and the presence of carboxylic acid moieties, the mechanism is not clearly understood. As a result of this discovery, considerable effort has been focused on overcoming this tendency, since perceived softness is a major factor in consumer acceptance of any tissue product.